A wide variety of implant formulations have been suggested in the art for the treatment of bone defects. In addition to traditional bone grafting, a number of synthetic bone graft substitutes have been used or explored, including malleable putties. In particular, malleable putties may be used to fill bone voids and stimulate regeneration of bone in a subject. The use of a composition having putty-like consistency facilitates the placement of the bone void filler into the bone defect site, which is frequently an irregular shape. To fill these voids, surgeons may take a bone void filler and trowel it into the defect or shape it by hand.
Many products have been developed in an attempt to treat this surgical need for a biocompatible bone putty, for example, autologous bone particles recovered from the patient are wet and viscous from the associated blood and this is packed into the bone void. While autologous bone is considered to be the gold-standard for healing bone defects, it requires significant additional surgery that results in potential adverse events associate with such surgery, which in extreme cases includes death.
Implant materials can benefit from the presence of scaffolding material, such as, biocompatible ceramics or other mineral scaffolds. However, biocompatible ceramics are generally hard, brittle substances, which makes it difficult to incorporate substantial levels into a composition that has a putty-like consistency. Addition of hard pieces of ceramic tend to disrupt the putty mass, producing a composition that is crumbly and lacks the cohesiveness desired for handling prior to implantation and for persistence after implantation.
Proteins, such as BMP-2, GDF-5 and BMP-7, have been shown to induce bone growth, but such bone growth is desirably restricted to a particular location in the subject being treated. Hence, it is preferable to confine these proteins to the desired treatment site. Unfortunately, this has proven difficult to do and as a result the use of these proteins has either been limited or has required a large amount of the protein to achieve the desired result.
What is needed is a moldable or flowable implant composition that may be used to apply therapeutic agents to a local area and retain them there for a prolonged period of time, for example, at least a week.
Any publications or references discussed herein are presented to describe the background of the invention and to provide additional detail regarding its practice.
Nothing herein is to be construed as an admission that the inventors are not entitled to antedate such disclosure by virtue of prior invention. Should there be a conflict, or apparent conflict, between the specification and any of the incorporated references, the specification takes precedence and the conflicting or apparently conflicting aspect of the reference is to be disregarded.